When a diesel engine won't start

[Sybarite]

My diesel would turn over but would not fire.

My mechanic friend injected engine oil into the air intake and it fired straight away.

This may be a well known method, but I didn't know about it so FWIW.....

 

[fisherman]

My diesel would turn over but would not fire.

My mechanic friend injected engine oil into the air intake and it fired straight away.

This may be a well known method, but I didn't know about it so FWIW.....

Standard procedure with some old Listers, fitted with an injection plunger. A plumber's gas torch is very effective.

 

[30boat]

Since it's not cold any longer your diesel should have started,unless the batteries were low and it was turning sluggishly on the starter.The oil restored the sealing at the rings improving compression.It could be that your bores/rings are worn,hopefuly not.If it goes on starting normally don't worry but if it happens again,check your battery first.If even with a good battery(and starter) it doesn't start easily it may be time to start worrying.It doesn't seem to me that it's a valves problem because the oil in the bores has no effect on them,only the rings.Does the engine emit blue smoke under acceleration?

 

[Sybarite]

Since it's not cold any longer your diesel should have started,unless the batteries were low and it was turning sluggishly on the starter.The oil restored the sealing at the rings improving compression.It could be that your bores/rings are worn,hopefuly not.If it goes on starting normally don't worry but if it happens again,check your battery first.If even with a good battery(and starter) it doesn't start easily it may be time to start worrying.It doesn't seem to me that it's a valves problem because the oil in the bores has no effect on them,only the rings.Does the engine emit blue smoke under acceleration?

The batteries are nearly new and fully charged. Bores and rings unlikely to be worn because the boat has been underused in recent years (house renovation on going). Normally once it gets going there is no problem in it restarting, so imo it's underuse which is at the heart of the problem.

 

[30boat]

The batteries are nearly new and fully charged. Bores and rings unlikely to be worn because the boat has been underused in recent years (house renovation on going). Normally once it gets going there is no problem in it restarting, so imo it's underuse which is at the heart of the problem.

It could be.Bore glazing can also be present.Scratches made by honing hold oil which helps compression.If your bores are smooth the oil will run off.Most problably it's just that the oil ran off with time and the bores were dry.

 

[bedouin]

This was the standard cold start procedure on the first diesel I had (a Coventry Victor). It had a little device on the side that would inject a few ccs of engine oil directly into the cylinder. I never worked out if that was just to improve the compression or whether the oil was easier to burn than diesel

 

[30boat]

This was the standard cold start procedure on the first diesel I had (a Coventry Victor). It had a little device on the side that would inject a few ccs of engine oil directly into the cylinder. I never worked out if that was just to improve the compression or whether the oil was easier to burn than diesel

Probably both.

 

[matthew99]

It's not immediately obvious to me, would you let me know how much oil (a teaspoon or more) and where do you put it (inside the inlet manifold or as near to)?

Whenever I want to make sure an engine starts, say after a long winter laid up, I will apply heat to the whole engine with a fan heater for about an hour beforehand.

Many thanks

 

[Sybarite]

It's not immediately obvious to me, would you let me know how much oil (a teaspoon or more) and where do you put it (inside the inlet manifold or as near to)?

Whenever I want to make sure an engine starts, say after a long winter laid up, I will apply heat to the whole engine with a fan heater for about an hour beforehand.

Many thanks

I didn't actually see him add the oil (I was in the cockpit starting the engine) but he said that he took the air filter off and added some oil in the air intake. Others here may be able to tell you more or one could test with a little at first and then add more as necessary.

 

[ProDave]

Isn't this what Easy Start was made for?

My BIL uses that to start his old MF tractor when cold.

 

[penfold]

The oil plunger on a petter ACW1 puts about 2-3cc into the inlet manifold, some chinese Yanmar L100 clones come with a similar arrangement and the operator manual advises using ~2cc of oil to aid starting.

 

[Sybarite]

Isn't this what Easy Start was made for?

My BIL uses that to start his old MF tractor when cold.

Yes. He asked me if I had any on board, but in the absence, it was engine oil.

 

[savageseadog]

I use a hot air gun or hair drier into the inlet manifold

 

[DanWash]

Please go out and need to be rescued ...... please go out and need to be rescued ...... :encouragement:

 

[Daydream believer]

Make a donation to the RNLI & perhaps one of their engineers might tell you what to do -- free of charge

 

[westernman]

I read somewhere that on old engines with worn piston rings, a squirt of oil into the air inlet helps the rings seal and dramatically increases compression.

 

[30boat]

I read somewhere that on old engines with worn piston rings, a squirt of oil into the air inlet helps the rings seal and dramatically increases compression.

That's true but the OP says the engine is not worn.

 

[Sybarite]

That's true but the OP says the engine is not worn.

Yes. Apart from this hiccup it works perfectly. 2200 rpm, 6 knots, 1.5l/hour. Apart from one time the cooling system needed to cleaned to avoid overheating.

 

[JumbleDuck]

Yes. Apart from this hiccup it works perfectly. 2200 rpm, 6 knots, 1.5l/hour. Apart from one time the cooling system needed to cleaned to avoid overheating.

If it hadn't been used for a while it could just have had sticking rings. The squirt of oil seals things enough to get it started and then head and motion free the rings off. Not uncommon in classic cars after a winter layup.